Apparatus for aerating viscous liquids



July 20, 1943. H. w. GREENUP EI'AL APPARATUS FOR AERATING VISCOUSLIQUIDS Original Filed ma 8, 1937 7 Sheets-Sheet 1 I NVENTOR Herald 1!.Guam p and llorrislohuston BY i KORN EYS July 20, 1943. H. w. GREENUParm.

APPARATUS FOR AERATING VISCOUS LIQUIDS Originfilfiled May 8, 1937 7Sheets-Sheet 2 Wm am m M W M m m ms m m m fl s July 20, 1943. H. w. GR EENUP ETAL 2,324,988

APPARATUS FQR AERATINGVISCQUS LIQUIDS Original Filed May 8, 1937 '7Sheets-Sheet 4 INVENTOR fiaroldmemnup an& Hon is John {ton BY I h fATTORNEYS y 1943. H.- w. C-E'REENUP ETAL I 2,324,988

APPARATUS FOR AERATING VISGOUS LIQUIDS Original Filed May 8, 1937 7Sheets-Sheet 5 l N finals nap 7 .BY Harris Johnston 7 Sheets-Sheet 6 H.W. GREENUP ET'AL APPARATUS FOR AERATING VISCOUS LIQUIDS Original FiledMay 8, 1957 July 20, 1943.

NVE-N TOR Jim-old Grunup an .fiorris Johnston :IZZR N 5Y5 July 20, 1943.H. w. GREENUP ET AL APPARATUS FOR AERATING VISCOUS LIQUIDS ori inl FiledMay a, 1957 '7 Sheets-Sheet 7 Patented July 20, 1943 arramrcs roaAERATING VISCOUS mourns Harold W. Greenup, Fall River, Mass., and NorrisJohnston, Alhambra, Calif., assignors to The Firestone Tire & Rubber.Company, Akron, Ohio, a corporation of Ohio Original application May 8,1937, Serial No. 141,580. Divided and this application October 9, 1940,Serial No. 360,388

2 Claims.

This invention relates to apparatus for aerating viscous liquids, andmore especially it relates to improved apparatus for frothing aqueousdispersions of rubber, such as natural latex, although any rubberdispersion can be processed by the apparatus of the invention.

The invention is of especial utility in the manufacture of vulcanizedcellular or sponge rubberwstructures wherein. the size-of thezvcells isan important consideration, said cells being the result of the airbubbles with which the unvulcanized rubber dispersion is impregnated. Bymeans of the present invention the size of the air bubbles may becontrolled.

This application is a division of our application for Letters PatentSerial No. 141,580 filed May 8, 1937, now Patent No. 2,244,616.

The chief objects of the invention are to provide improved apparatus forfrothing rubber latex. More specifically, the invention aims to producea latex froth wherein the air bubbles are of small unit size; to providea system for the continuous production of latex froth; to obviatecoagulation of the latex resulting from violent impact thereof with theaerating apparatus; and

.to provide against splatter of the latex so that aeration thereof my beeffected in open vessels, and mechanical diiliculties arising from latexin machinery bearings will be avoided. Other objects will be manifest asthe specification proceeds.

Of the accompanying drawings:

Figure 1 is a plan view of apparatus embodying the invention, in itspreferred form;

Figure 2 is a side elevation thereof;

Figure 3 is a section on the line 33 of Figure 1 and Figure 4;

Figure 4 is a section on the line 44 of Figure 2 and Figure 3; a

Figure 5 is a section, on a larger scale, on the line 5-5 of Figure 2;

Figure 6 is a section, on a larger scale, on the line 6-6 of Figure 2;

Figure 7 is a section, on a larger scale, on the line 'I-| of Figure 2;

Figure 8 is a side elevation of another embodiment of the invention;

Figure 9 is a vertical section through a portion of the structure shownin Figure 8;

FigurelO is a section on-- the line |0-l0 of Figure 9;

Figure 11 is a plan view of still another embodiment of the invention;and

Figure 12 is a section on the line I 2--l2 of Figure 11.

Briefly stated, the improved aerating apparatus consists in thecombination of means for forming a continuous stream of compoundedrubber latex, means for eifecting a gravity induced flow of latex bydirecting it in a course extending from a higher to a lower level, andmeans for subjecting the latex to a beating or whipping action atsuccessive local regions longitudinally of saidwourse.

The preferred apparatus is shown in Figures 1 to 7 inclusive, and aplurality of apparatus units may be arranged in side by side relation toconserve floor space, and to permit the use of structures common to twoor more units,.as is clearly shown in Figure 1 The apparatus comprisesan open framework l5 that carries a tank It at one end thereof and at alow elevation, said tank extending entirely across the framework andconstituting a receptacle for receiving liquid latex that overflows froma plurality of receptacles p0- sitioned at a higher elevation, aspresently will be explained. The tank I6 is provided with a closabledrain pipe ll in its bottom for removing liquid therefrom. Mounted uponthe top of the framework ii, at the same end thereof as the tank l6, aretwo receptacles or tanks l8, It for receiving a supply of compoundedliquid latex thatsub'sequently is to be aerated. In'each' receptacle I8is an agitator is driven by a motor 20 atop the receptacle, saidagitator keeping the latex in the receptacle in motion so as to maintainthe latex at uniform consistency. The two receptacles IB- supply latexto four units of aerating apparatus, and positioned between the latterand said receptacles are devices for assuring uniform flow of latexnotwithstanding variations in the head of liquid in the receptacles.

Said devices comprise small distributor receptacles 2|, 2|, each ofwhich is associated with a receptacle l8 and receives latex therefrom bygravity flow through a suitably valved pipe 22. The bottom of eachdistributor receptacle is provided with two delivery pipes or nozzles23, 23 that are spaced apart so as to be positioned over the receivingends of respective aerating units. The lower end of each pipe 23 isprovided with a removable apertured cap 24 that may be replaced by othercaps having apertures of different sizes whereby the size of the streamof latex flowing to the aerating units is controlled. Below the level ofthe inlet pipe 22, each distributor receptacle is provided with anoverflow port 25 connected by a pipe 26 with the overflow tank It. Inoperation, latex is delivered to the distributor receptacles throughpipes 22 faster than the aerating units is achieved.

The four aerating units shown are arranged in pairs in that they deliverthe frothed latex into but two delivery trough at their delivery ends.In other respects the units are separate from each other, and areidentical in structure so that a description of one will sumce for all.As shown in Figures 2 and 3, the framework I5 includes a plurality ofparallel frame members He that extend substantially from end to end ofthe framework, and slope somewhat downwardly from the receiving end ofthe apparatus toward the delivmy end thereof. suspended between a pairof adjacent frame members l5a is a trough-like structure consisting of aseries of contiguous, open compartments 30,- of which adjacentcompartments are separated by respective walls or partitions 3|, 3|. Thebottom of each compartment is horizontally disposed so that thestructure presents a stepped appearance, and said bottoms aretransversely rounded or concave, and provided with respective suitablycapped drainage orifices 32. As is most clearly shown in Figures 3 and4, the partitions 3i are deeply notched, as

at 3l a, to permit liquid in each compartment 30 to overflow into theadjacent lower compartment. The notches 3ia are of different depths,varying from a relatively deep notch in the partition between the twouppermost compartments to a relatively shallow notch on the deliveryside of the lowermost compartment. The arrangement is such that thesuccessive compartments 30, from the receiving toward the delivery endof the apparatus, are of progressively increased capacity. Since all ofthe compartments are of the same area, this means that the depth of theliquid in the compartments at the lower end of the series is greaterthan the depth of the liquid in the upper compartments. The uppermostcompartment 3! is below one of the delivery pipes 23 of a distributorreceptacle 2 l.

Positioned within each compartment 3.0 of the series is a rotary heateror whip which may be of the type and size commonly in household use. Asis most clearly shown in Figure 3, such beaters comprise two rotarybeater elements that are suitably geared together withina housing 36.The .latter is adjustably mounted upon an upright stem or stud 31 thatis carried by a bracket arm 33, said arm being secured to a frame memberl5a at one side of the compartment. For driving the beater 35, the shaftor stemof one of the rotatable elements thereof is provided with agrooved pulley 39 about which is trained a driving belt --4ll, thelatter also being trained about a grooved pulley 4| that is mounted upona drive shaft 42. The drive shaft 42 is co-extensive with the series ofcompartments 3', being journaled in a plurality of'bearing brackets 43,43 that are mounted upon a frame element lie, on the opposite side ofthe compartment from the frame element that carries bracket arms 33. At,its upper end the drive shaft 42 is coupled to the shaft of an electricmotor 44 that is mounted upon the framework 15 below the receptacles l3.The arrangement is such that one motor 44 drives all of the heaters 35of one aerating unit, which beaters whip the liquid latex into a froth.

At the delivery end of the aerating unit, the

lowermost compartment 30 thereof discharges into an elongate spillway ortrough 41, said trough extending transversely of the apparatus so as tofunction as a spillway for two of the aerating units. At one of its endsthe trough 41 is provided with discharge spout 48 through which theaerated fluid will flow by gravity, said spout being pivotally mountedso as to be angularly movable to alternative positions, whereby it maybe caused to discharge alternatively into different receptacles.

Positioned at the delivery end of the apparatus are four receptacles 50,50 for receiving aerated liquid from the delivery spouts 48. As shown inFigure 5; each receptacle 5B is a cylindrical tructure thathas aclosable, axial drainage port H in its bottom. The receptacle 50 isrotated upon its axis, and means is provided for stirring the frothedlatex that flows thereinto, to maintain the latter at uniformconsistency and to assure proper admixing-therewith of otherconstituents, such as a coagulating medium, that i introduced into abatch of froth immediately before the froth is poured into a. mold. Theswingable feature of each spout 48 makes it possible for the spout todischarge into one receptacle 50 while the adjacent receptacle isremoved from the apparatus' for emptying and cleaning.

For eflecting rotation of the receptacles 50, each of them is mountedupon a turntable 52 that is supported upon'a bearing structure 53carried by a shelf 54 on the framework I5. The turntable 52 isperipherally grooved to receive a driving belt 55 that also passesaround a driving pulley 56 that is mounted upon a shaft 51, the latteralso carrying a sprocket 58. The latter is engaged by a sprocket chain59 that is driven by a sprocket 50 of a reduction gear device GI, andthe reduction gear device is driven by a motor 62 to which it iscoupled, said motor being mounted upon framework l5, near the bottomthereof. The turntable 52 is formed with an axial opening to receive apilot structure 63 on the bottom of receptacle 50for centering thereceptacle onthe turntable. There is but one motor iii, re-

duction gear device 6! and shaft 51, the latter carrying four pulleys 55by means of which all four receptacles 50 are rotated.

For stirring the contents of each receptacle 50, an agitator 65 isprovided, which agitator has an operative position within the receptacleand an inoperative position above the same. The agitator 65 is somewhatsimilar to the beaters 35, but is larger and longer. It comprises tworotary elements that are geared together at their upper ends, the gearsbeing enclosed in a housing structure 65. The latter comprises a topplate that projects laterally of the housing, and is formed with a pairof spaced apart apertures in which are receivable a pair of studs 51, 61that project upwardly from a cross-member 68 carried by the frameworkl5. The arrangement is such that the.agitator will be supported bycross-member 63 when it is in operative position, the studs 6!preventing angular movement of the agitator from torque reaction duringthe operation thereof.

The agitator 65 is driven by means of a vertical drive shaft Illconnected at its lower end to one of the rotatable elements of theagitator. The

with gear I3 is a bevel gear that is directly connected to the shaft ofa motor I6 so as to be driven thereby, said motor being mounted upon theshelf 12 exteriorly of the gear box H. The upper end of the shaft 10 isprovided with a loop 11 whereby it may be manually grasped for liftingthe shaft and thereby raising the agitator out of the receptacle 50, asindicated in broken lines in Figure 5. For retaining the agitator inraised, inoperative position a pair of pendulous hooks I8, 18 aremounted upon the under side of shelf 12, said hooks being adapted toengage the under side of housing structure 66, in the elevated positionof the latter, as shown in Figure 5.

Because the notches 3Ia of the partitions 3| are of greater depthbetween the compartments 80 at the upper or receiving end of the series,it follows that the depth of the liquid in the respective compartmentswill be progressively greater toward the lower or delivery end of theseries. And this differential in depth will be accentuated by reason ofthe frothing of the liquid, which increases the viscosity of the liquidand causes it to flow from one compartment to the next in aprogressively thicker stream. All of the heaters 35 are positioned inthe respective compartments 38 at the same distance from the bottomsthereof, with the result that they are thereby'immersed to differentdepths in therliquid therein. At the upper end of the series ofcompartments the beater is only about half submerged. In the lowermostcompartment the beater is disposed well below the level of the froth.

The action of the heaters in the liquid latex is to whip the latter, andset up a circulation of the liquid which causes it to flow outwardlyaway from the beater near the bottom of the container, thence upwardlyalong the sides of the container, and then inwardly toward the beater atthe top of the body of liquid. Because it is desirable that all theliquid in each container be set in circulation, the size of thecontainer bears a definite relation to the size of the beater. Bestresults are obtained if the greatest width of the container is not morethan four times the greatest width of the beater. The speed at which thebeaters 35 are driven also is important, since it must be great enoughto produce a substantial vortex.

Experience has shown that .a speed of 1,100

R. P. M. gives satisfactory results. Because of the latter, and becausethe heaters at the receiving end of the series of compartments are notcompletely submerged in the latex, the result of the beating is toimpregnate the latex with a multiplicity of relatively lar e airbubbles, thus forming a froth. As the latter cascades to the other,lower compartments 30, it is subjected to successive whipping actions bythe other heaters. Because the latter are completely submerged in thefroth, their action does not draw more air into the froth, but breaks upand divides the bubbles already therein so that the froth that flowsinto trough 41 is extremely light and viscous, and of much greatervolume than the stream flowing from nozzle 23.

Splattering of the latex during the frothing thereof is undesirable forthe reason that it causes coagulation of the particles that aresubjected to violent impact. The viscosity of the latex is a factor thataffects splatter, so also is the peripheral velocity of the beaterelements. Since the beaters are required to rotate at sufficient speedto cause the latex to assume a vortex, it is necessary that the size ofthe heaters be as small as is practicable. It is for this reason thatbeaters of the size usually found in domestic service are preferred.

The apparatus described achieves the continuous production of aeratedlatex. The compounded liquid latex flows in a uniform stream into theuppermost of the compartments 38,

where it is whipped into'a froth containing relatively large airbubbles, and overflows therefrom into a succession of other compartmentswhere the whipping is repeated to reduce the size of the said airbubbles. From the lowermost compartment 30 the froth flows through spout48 to one of the receptacles 50 where it is continuously stirred until asufllcient amount accumulates to constitute a batch. Thereupon otheringredients, including a coagulant, are stirred into the batch, afterwhich the drive of motor 16 is stopped, the agitator is elevated toinoperative position, and the receptacle 50 removed from the apparatusand its contents disposed of. Before the receptacle 50 is removed asdescribed, the spout 48 is swung angularly so as to discharge into anadjacent receptacle i8.

Aside from the advantages accruing from continuous production, theinvention provides for the mechanical frothing of latex, it provides asuperior product due to the absence of frothing agentstand it achieves:the othereadvantages set out in the foregoin statement of objects.

The embodiment of the invention shown in Figures 8 to 10 inclusiveconsists of a single apparatus unit that is essentially similar to aunit of the apparatus previously described, so that a detail descriptionof the modified structure will not be required. The primary differencebetween the two embodiments is the feature of an individual drive foreach of the beater devices. As is shown most clearly in Figure 10, eachbeater 88 is driven by an electric motor that is mounted within a.housing 8|, said motor being connected with a source of power throughconductor cord 82. The housing 8| is mounted upon the overhangingportion of an inverted L-shaped bracket arm 83 that is bolted orotherwise secured to an angle member 84 that constitutes a part of theframework of the apparatus. Preferably the attaching bolts extendthrough a slot 85 extending longitudinally of the bracket arm, wherebyvertical adjustment of the latter is effected. The arrangement permitsthe beater to be positioned at the optimum distance from the bottom ofthe latex compartment. Fig. 9 most clearly shows the relation of theheaters to the height of the partitions between the adjacentcompartments.

The beaters 88,, like all household beaters, are equipped with means forvarying their speed, the usual arrangement providing three differentspeeds. 'This makes it possible to drive the beaters at optimum speed,or at differential speeds if better results may be obtained thereby.Thus the modified embodiment of the invention possesses greaterflexibility than that previously described.

The modified embodiment of the invention shown in Figs. 11 and 12differs essentially from those previously described in that it does notproduce a continuous supply of froth. It comprises a table 88 of whichthe middle portion consists of a-circular-turntable 88 that rests upon abearing structure carried by a light framework 8l secured to the underside of the table. The turntable. 89 supports an annular trough 92 thatis centered upon the turntable by means of a plurality of upstandinglugs 93 on the latter. the turntable 89, is an annular series orelectrically operated heaters 9|, 94. Each of said beaters is providedwith a base member 95 to which it is pivoted, the arrangement being suchthat the heaters may be positioned within the trough 92, as shown, ortilted backward away from the trough to'permit the latter to be liftedofi the turntable. The turntable 89 and trough 92 are rotated abouttheir common axis by means of a drive belt 91 that is trained about theouter periphery of the trough, and about a drive pulley 98 that iscarried upon the shaft of a motor 99, the latter being mounted, upon avertical axis, upon the side of table 88.

In the operation of this embodiment of the invention, a quantity ofcompounded rubber latex, suflicient almost to cover the beater elementsas shown, is placed in the trough 92. The latter is then rotated and theseveral heaters put into operation, with the result that the liquid inthe trough is carried past the beaters in continuous succession, saidbeaters whipping the liquid into a froth. When the froth attains thedesired consistency, the operation is concluded,

the beaters are tilted, and the trough removed from the turntable andemptied.

It will be seen that the apparatus depicted in Figures 11 and 12 is notcontinuous in operation, that it prepares but one batch at a time, andthat the size of the batch is definitely limited. The

quality or the froth produced, however, is satisfactory, and otherobjects or the invention are achieved. 7

Other modification may be resorted to without departing from the spiritof the invention, or the Mounted upon the table top, outwardly of scopeof the invention as defined by the appended claims.

What is claimed is:

1. In apparatus for aerating liquids, the combination of a series ofcontainers for liquid so arranged that overflow from each containerenters the adjacent container of the series, means for continuouslysupplying liquid to the container at one end of the series, and a beaterin each of said containers, the relation of the heaters to the level ofthe liquid in the containers varying from partial submergence of thebeater at the liquid-receiving end of the series to complete submergenceof the beater at the other end of the series.

2. In apparatus for aerating liquids, the combination of a series oflaterally adjoining containers for liquid arranged in a descendingseries so that overflow from each container enters the next lowercontainer, adjacent containers of the series being separated by apartition, the partitions at the upper end of the series extending at aless'height above the bottom or their respective containers than thepartitions at the lower end thereof to provide a progressivelyincreasing HAROLD w. GREENU'P.

NORRIS JOHNSTON.

